Need a new amplifier. Need a good match for my Audio Research LS7 preamp

If buying used is an option, the older McIntosh SS amps may give you the sound you're looking for within your budget.

Are you planning on upgrading speakers anytime in the near future? If so I’d do that first rather than trying to tame the sound with an amp that may be too warm sounding if you get better speakers later.

That said, there’s a nice Classe CA300 for sale a little above your current price target that should tame the top end a bit along with providing a big boost in power for higher volume listening. There’s also a McCormack DNA1 with Steve’s silver upgrade mods at a bit under your price target. Not a warm sounding amp -- more neutral IME -- but should provide significantly more refinement to your top octaves versus the Arcam and may well also help with dynamics and separation (i.e. less congestion) at higher volumes. This is also an amp that you could pair with much better speakers in the future and still be more than fine, or you could even upgrade amp to one of Steve’s higher levels if you want even more.

Anyway, hope this helps and best of luck.

@hansk46 .....very good point.  IIRC that would rule out the Muse.  Belles and Classe still viable options.  soix's McCormack recommendation is even better imo as you do get a more refined and neutral amp with the correct input impedance.  The McCormack is an amp that can be partnered with many different speakers.

Also IIRC, the ARC LS7 has a higher than average gain ( at least mine did ) which could be contributing to more glare and brightness especially at higher volume.

Best and keep us posted.

j200jr,
The later Classe CA-200 with the heat sinks on the side are reported to be much better than the earlier model with the heat sinks on the back because of "distributed capacitance" - caps distributed over the circuit board instead of just at the power supply (as I understood it), and equal to the replacement CA-201. There was a later version of the CA-201 that was said to be much smoother. It has aluminum "pillars" at the front corners. I had the earlier version and it was a bit coarse. Classe was said to be a good match for B+W.
You haven’t mentioned your cables so I will add that better cables could give you more clarity. Recently I upgraded my speakers and have a bit of glare at higher volumes too. Until I can demo cables I have stuck Post-it notes over the tweeters. It works surprisingly well, costs nothing and puts the fun back into listening. Good luck on your quest.
Bill